Figure 1. Peripheral nerve anatomy, including vascular supply.

Digital light photomicrograph of an axial section of a normal adult sural nerve (plastic embedded semi-thin axial section stained with Toluidine Blue and counterstained with Basic Fuchsin) showing the three compartments in peripheral nerves, and endoneurial microvessels (EMV, black arrowheads) that form the BNB (A). This structural organization is further illustrated in (B), with individual nerves supplied by extrinsic vessels, called vasa nervorum, which form a vascular anastomoses and penetrate into the epineurium, resulting epineurial macrovessels. These macrovessels cross the perineurium, forming endoneurial microvessels. The anatomical organization of endoneurial microvessels and the perineurium is further illustrated, with restrictive tight junctions between the endothelial cells and innermost perineurial myofibroblasts respectively.